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Built one a while ago . never did get it working . Now have more time to get back to it. Used mostly the Ceri@tone layout but with Larry grounding.

The issue is very different bias voltage between the two tubes (did swap them with each other ) issue stayed with the socket. checked the grid leaks there within .1 k of each other.

There is a very weak clean signal getting trough over all hum

From the look of the voltage chart seems to be an issue with the pi . ( i just don't see it) need another set of eyes to look at it. or i did fry the output transformer with the mistake below

I did make a major mistake when i first built in that i used a plate wire for to the b+ (did check the resistance of the output transformers after) seems ok within the + - 20% that hammond specifies with in 1.5 r of each other to the ct

1 2 3 4 5 6 7 8 9

v1 209 - 1.6 3.17a 3.17a 195 - 1.6 3.17a
v2 127 1 1.3 3.17a 3.17a 2.97 127 129 3.17a
v3 168 58 59 3.17a 3.17a 175 42.5 59 3.17a

v4 19mv 3.17a 421 420 -52.8 3.17 19mv
v5 34mv 3.17a 424 424 -47.8 3.17 34mv

v6 used a 5u4gtb 4.93v rms heater 347 to each plate 119 ac wall

Also did try a known set of 6l6s still had the major variance in bias curent

Will post some pictures shortly

Did you confirm the 1R current sensing resistor is actually 1R ?
I will pull my JTM voltages and post them for you.
Best to check all the resistances and grounds. I think you know that...
If the OT measures OK, then it probably is. You could do a check and calculate the impedance to be sure.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Yeah there 1r's. measured them 3 times.
And really like having a fluke meter, probes measure .1R and the resistors are 1.1R (think I'm good there)

I Did measure out all the resistor in the power amp an pi every thing looks good
All grounds to grounds are good.

Getting it better now.
With coffee my brain re engaged used my own advice divide and conquer .

decouple the pre amp and pi worked out the bias issue.

Seems to be something funky with the stby switch ht fuse holder (not providing enough current )

with the preamp de coupled and the power amp biased no noise until i reconnect the pre amp

So a little more work and I'm there

Thanks for info.

Could you link me to the impedance calculation for the transformer . don't know it;(

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

JTM 45 Voltages

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Thanks all i need now is time to get back to this